Many electronic devices or systems, such as computers, network devices, tablets, and cellular phones, have thermal sensors to monitor the temperature of the device or system. For precise measurements of temperature, conventional thermal sensors in such devices or systems usually rely on parasitic PNP components (e.g., parasitic PNP bipolar transistors). However, in some fabrication technologies, the quality of such PNP components may degrade drastically due to factors such as micro-defects in junctions (e.g., emitter-base junction) in the PNP components. Further, some conventional thermal sensors may need multi-point trim for sensing adjustment in order to meet specific measurement accuracy. Moreover, in some fabrication processes, options for forming such PNP components in the device may be limited or may be non-existent. Thus, for the at least reasons mentioned herein, designing thermal sensors in some conventional devices may pose a challenge.